Study of a Control Method of Fuel cell Inverters Connected in Parallel and Verification Test Result of an Isolated Micro grid

The "new energy plant" had been built at the Aichi EXPO. 2005 site as part of the "demonstrative project of regional power grid with various new energies". The plant includes three types of fuel cells, a photovoltaic power generation system and a sodium sulfur (NaS) battery. One of the purposes of the demonstrative project is to achieve isolated operation of a micro grid without rotating generators. These new energy generators and battery are connected to the micro grid via inverters. In isolated operation, the system voltage and frequency are determined by four fuel cell inverters connected in parallel. This paper presents the control strategies, especially load share between inverters, for isolated operation of a micro grid configured with some new energy generators. Simulation results and verification test results are also shown in this paper.